From: Yann Collet <cyan@fb.com>
Date: Fri, 25 May 2018 21:52:21 +0000 (-0700)
Subject: slightly nudge choices towards less sequences
X-Git-Tag: v1.3.5~3^2~41^2
X-Git-Url: http://git.ipfire.org/gitweb/gitweb.cgi?a=commitdiff_plain;h=refs%2Fpull%2F1141%2Fhead;p=thirdparty%2Fzstd.git

slightly nudge choices towards less sequences

also slightly improve some strange detrimental corner cases.
---

diff --git a/lib/compress/zstd_opt.c b/lib/compress/zstd_opt.c
index 2a699c2ac..e66019aa8 100644
--- a/lib/compress/zstd_opt.c
+++ b/lib/compress/zstd_opt.c
@@ -282,6 +282,8 @@ ZSTD_getMatchPrice(U32 const offset,
         price += (ML_bits[mlCode] * BITCOST_MULTIPLIER) + (optPtr->matchLengthSumBasePrice - WEIGHT(optPtr->matchLengthFreq[mlCode], optLevel));
     }
 
+    price += BITCOST_MULTIPLIER / 5;   /* heuristic : make matches a bit more costly to favor less sequences -> faster decompression speed */
+
     DEBUGLOG(8, "ZSTD_getMatchPrice(ml:%u) = %u", matchLength, price);
     return price;
 }